Forming die



FORMING DIE Filed Nov. 1, 1959 MIL 5 Rn Y fiww N 2 fm m J Patented Sept.29, 1942 FORMING DIE Edwin H. Kotcher, Detroit, Mich., assignor to TheMurray Corporation of America, Detroit, Mich., a corporation of DelawareApplication November 1, 1939, Serial No. 302,419

3 Claims.

My invention relates to forming dies for sheet metal, and particularlyto a set of dies employed for drawing a sloping surface in a recessedelement, more particularly, the sloping surface at one end of a bathtub.

In the pressed metal art for working sheet metal to produce a bath tub,difllculty has always been experienced when attempting to produce asloping end on the wall of the tub. Dies have been designed heretoforewhich telescope longitudinally of each other for attempting to produce asloping tub end as the die was moved downwardly. The concentration ofthe large downward pressure at the corner of one of the die sectionswhich was to be moved normal thereto would cause tremendous unitpressure which would overwork the metal being drawn, thereby producingthin, distorted, and ruptured walls. It was for this reason that sheetmetal bath tubs were produced with vertical walls at both ends, or weremade of two or more stampings which were welded together.

In practicing my present invention, I construct a female die portion,the contour of the entire bottom of which is formed to the shape of thebottom of the tub to be drawn. At the end of the male die portion whichis to form the sloping surface, I provide a slide disposed angularly tothe downward path of movement of the die and to the sloping surface tobe produced. The end of the slide is projected downwardly to besubstantially in the plane of the lower comer of the die body.Resistance means, such as fluid, springs, and the like, may be employedto offer resistance against retractive movement of the slide conformingto the amount of pressure required to produce the drawing operation.Adjustable means regulates the pressure so that no more than the amountof energy required to actually draw the metal is utilized in retainingthe slide against the retractive movement. In view of the slope of theslide at an angle to the downward movement of the die body and at afavorable angle to the slope of the tub Wall, the pressure required toretract the die is materially reduced over that when the die is dividedto be moved normal to the movement of the die during the drawingoperation.

Accordingly, the main objects of my invention are: to provide a set'ofdies which efliciently draw metal to form a receptacle having a slopingend; to provide a male die for drawing a recess in a metal sheet whichhas a slide in one end which is retractable in a path at an acute angleto the path of movement of the die; to provide a male die for drawing arecess in sheet metal having the shape of said recess, and having oneend wall mounted as a slide, at an acute angle to the path of the diemovement and the sloping surface, for producing a sloping surface in thewall of the recess; to dispose a slide in one end of a die at an acuteangle to the path of movement to the die and provide resistance meansfor opposingthe slide retraction as the die is moved downwardly toperform a drawing operation, to provide an adjustment for the resistancemeans of the slide so as to vary the pressure of the slide during itsretractive movement; and in general, to provide a set of dies fordrawing sheet metal to form a receptacle, having a sloping side, such asfor a bath tub, which is simple in construction, positive in operation,and economical of manufacture.

Other objects and features of novelty of my invention will be eitherspecifically pointed out or will become apparent when referring, for abetter understanding of my invention, to the following description takenin conjunction with the accompanying drawing, wherein:

Figure l is a sectional view of a set of dies for drawing a recess in asheet of metal, embodying features of my invention;

Fig. 2 is a sectional view of the die set illustrated in Fig. 1, takenon the line 1-! thereof;

Fig. 3 is a plan view of the die set illustrated in Fig. 1; and,

Fig. 4 is a sectional view of the stamping drawn by the die setillustrated in the foregoing figures.

While the principle of operation of the set of dies embodying myinvention may be employed in any metal drawing operation for forming areceptacle having a sloping side wall, for the purpose of illustrationthe die set hereinafter described is employed for drawing a sloping wallin one end of a sheet metal bath tub. The female die ID is recessed toconform to the shape of the tub while the male die II has the bottomsurface l2 and rear surface I3 shaped to mate with the recess in the dieIt. A slide I4 is mounted in the male die II, the lower edge of which isdisposed above the corner [5 of the die body.

illustrated in Fig. 1, the end 22 of the slide is substantially in theplane of the corner 23 of the die H so that upon the initial drawing ofthe metal the two corners operate simultaneously.

The female die III is preferably bolted to the base of a press, whilethe male die II is bolted to the movable head thereof. A clamping block24 has an aperture 25 through which the die H operates and suitablepressure means, not herein illustrated, forces the block downwardly uponthe initial movement of the head against the edges 26, of the metalsheet to securely clamp the sheet before the corners 22 and 23 of thedie H contact and begin the drawing operation. The slide II on the endof the dies ll produce the drawing of the metal forming the sloping wall21 of the tub. The angular position of the slide is such that a minimumamount of resistance is offered to its retractive movement against thepressure of the spring I8 as the die H moves downwardly. This angularposition is the resultant of the direction of the path of movement ofthe die and the direction of the slope of the wall of the tub.

By providing a pressure a fluid, spring pressure, or the like, which isadjustable, the proper While I have illustrated the die as having aslide which is spring pressed, it is to be understood that a cylinderand piston may be employed, or other means utilized. for controlling theamount of pressure on the slide. Suitable valves may be employed forregulating the fluid pressure so that the resistance offered to theretra-ctive movement of the slide may be accurately adjusted. By havingthe toe I 5 of the male die ll form one corner at the bottom of the tub,the shape of the tub is accurately duplicated and strain is therebyeliminated from the end 22 of the slide. A further advantage ofemploying a slide above the end I5 of the die resides in the open spaceprovided about the slide which permits the air, which would otherwise betrapped, to escape from between the sheet of metal and the male die. Itwas necessary heretofore to provide vent openings in similar large diesto relieve the pressure of air built up ahead tub and hence avoids anobjectionable gap in the die set at the sides of the tub beyond theinner end of the slide, which would otherwise result if the angle ofinclination were not sufllcient to enable the inner end of the slide toclear the top of the opposite end of the tub. It will be obvious that,in order to simultaneously iron the entire periphery of the tub, theangle of movement of the slide from the vertical must at least equal,but be opposite to, the angle of inclination of the end wall of the tubfrom the vertical.

While I'have described and illustrated but a singl embodiment of myinvention, it; will be apparent to those skilled in the art, thatvarious changes, omissions, additions, and substitutions may be madetherein without departing from the spirit and scope of my invention, asset forth in the accompanying claims.

What I claim is:

1. A set of dies relatively movable vertically for drawing a bath tubhaving a sloping end wall, including, a female die having a recess theshape of the outer contour of the tub, a male die corresponding in shapeto said tub except for the sloping wall portion which is recessed, asloping wall die portion mounted in the recess of the male die formovement at an angle disposed between a normal to the sloping wall andan angle to the vertical substantially equal to that of the sloping wallbut on the opposite side of the vertical from the sloping wall.

2. A set of dies relatively movable vertically for drawing a bath tubhaving a sloping end wall, including, a female die having a recess theshape of the outer contour of the tub, a male die portion correspondingin shape to said tub except for the sloping wall portion which isomitted, a sloping wall die portion for said male'die, means formounting said die portion on said male die for movement at an angledisposed between an angle to the vertical substantially equal to that ofthe sloping wall on the side of a vertical away from the sloping walland an angle from the horizontal formed by a line extending from thebottom edge of the sloping wall of the tub to the top edge of theopposite end of the tub.

3. A set of dies for drawing a bath tub having side walls and a slopingend wall extending between said side walls, including, a female diehaving a recess the shape of the outer contour of the tub, a male diecorresponding in shape to said tub except for the sloping wall portionwhich is recessed, and a sloping wall die portion of the full width ofsaid sloping wall and mounted in the recess of the male die for movementat an angle to the direction of movement between the male and femaledies, said angle and the length of the sloping die portion being suchthat the entire end opposite to the end which engages the sloping wallextends beyond the top edge of the tub at the end of the drawingoperation, and said angle being opposite to and at least as great as theangle of said sloping wall from said direction of movement.

EDWIN H. KOTCHER.

